Great Schism

The Great Schism was the break of communion between the Catholic church of the West and the Orthodox church of the East that occurred in 1054 following centuries of disputes and smaller schisms. The schism led to the formation of two separate churches that ceased to follow the same practices, and the Catholic religion became rooted in Western, Northern, and Southern Europe, while the Orthodox religion became the main religion of Eastern Europe.

History
In 1053, the Battle of Civitate and the ensuing conquest of southern Italy by the Catholic Normans led to the forced closure or conversion of Greek churches in the region, which angered Ecumenical Patriarch Michael I. He reacted to this provocation by ordering the closure of all Latin churches in Constantinople, cutting short any attempt at conciliation. In 1054 the papal legate of Pope Leo IX arrived in Constantinople to speak with Michael. Leo insisted that the Donation of Constantine, the statement (which was secretly forged) of Constantine the Great that the leadership of Christendom lay with the pope, should be enforced and instructed Michael to recognize Catholicism as the head of the church. Michael refused, so Humbert of Silva Candida excommunicated Michael, precipitating the schism.

The two churches were never to rejoin, with the Massacre of the Latins of 1082, the Sack of Thessalonica in 1085, the Crusades, and the Sack of Constantinople in 1204/the replacement of the Byzantine Empire with the Latin Empire as the rulers of Constantinople preventing relations from being healed. Today, the two religions are still divided; this went to show that the Great Schism of 1054, which lasted 1,000 years, was not going to be solved like the schisms of the Dark Ages that may have lasted less than 100 years.